A lectin with strong hemagglutination activity was isolated from roots of Sophora flavescens Ait. by extraction, fractionation with (NH 4) 2SO 4, ion-exchange chromatography on DEAE-Sepharose and followed by gel filtration on Sephadex G-150 and HPLC assay. The purified lectin showed a single protein band on PAGE and SDS-PAGE . The molecular weight of S. flavescens lectin was 32 kD when SDS-PAGE and Sephadex G-100 was used. The lectin agglutinated rabbit red blood cells at 0.97 μg/mL and showed no specific agglutination with any type of human erythrocytes. The hemagglutination activity could be inhibited by mannose and levulose and slightly by glucose and maltose. The SFL contained 2.89% neutral saccharide. It could inhibit apparently the growth of the mycelium of Gibberlla saubinetii （Mont.） Sacc.,Piricularia oryzae Cav. and Fusarium vasinfectum Atk. at the dosage of 62 μg. It was determined by Edman that the sequence of the N-terminal thirty amino acids was: T/A/VDXLXFTFSDFDPNGEDLLFQGDAHVTSNN.

Free polyamine levels (spermine (SPM), spermidine (SPD), and putrescine (PUT)) were determined using thin-layer chromatography and fluorometric method in loquat (Eriobotrya japonica Lindl. cv. Dahongpao) fruits stored at 1℃ and 12℃ and in postharvest SPM treated fruits stored at 1℃ respectively to investigate the relationship between changes in polyamines and chilling injury. In the loquat fruits stored at 1℃, SPM level decreased gradually in the first two weeks, then increased sharply and reached a peak value after three weeks, thereafter it decreased rapidly. SPD level decreased steadily during the first three weeks and increased significantly afterwards. PUT level evolved in a similar way as the SPM level did except that it increased slowly in the first two weeks. The fruit showed symptom of chilling injury manifested as flesh leatheriness after three weeks. However, no significant increase and decrease of these three polyamines was detected during storage at the nonchilling temperature (12℃). The SPM-treated fruits maintained high levels of SPM and SPD and remained low level of PUT during storage at 1℃, and no symptom of chilling injury was observed. These results suggested that the increase in SPM level in response to chilling exposure might serve as a defense mechanism against chilling injury while the accumulation of PUT could be a cause of the stress-induced injury and the increase in SPD level could be a consequence of this kind of stress.

The oxygen evolution, thermal dissipation, and photochemical energy storage of three hybrid poplar clones, namely the triploid clone B342, the diploid clone B11［( Populus alba×P. glandulosa)×(P.tomentosa×P.bolleana)］ , and the triploid clone B346 ［ (P.tomentosa×P. bolleana)×(P. alba×P.glandulosa )］, under light stress were studied using photoacoustics. The oxygen evolution signal and photochemical energy storage varied negatively with the pretreatment-PFD (photon flux density), whereas the thermal signal varied positively with the pretreatment-PFD. Photochemical energy storage was reallocated to PSⅡ more than to PSⅠ, while the photochemical energy storage in PSⅠ was more stable than that in PSⅡ when subjected to light stress. The inhibitors streptomycin (SM), dithiothreitol (DTT) and sodium fluoride (NaF) could all affect the oxygen evolution signal. Clones B11 and B342 were more resistant to light stress than clone B346.

The ultrastructural changes in leaf cells of submerged maize (Zea mays L.) were observed. After 2 h under submergence, an inward collapse of tonoplast was immediately observed while other cell components remained unaltered. After 6 h under submergence, the chloroplast envelope started to degrade and the inward collapse of tonoplast became more prominent. Until 12 h under submergence, localized splitting of the tonoplast appeared; the stromatic thylakoid membrane of the chloroplast started to be vacuolated when its envelope underwent further degradation. With prolongation of submergence to 18 h, the injury of chloroplast was enhanced. As the envelope was completely destroyed and disappeared and degraded the stromatic thylakoid membrane degraded. Meantime, the mitochondrial and nuclear membrane also started to be destroyed. During 24-48 h under submergence, the chloroplast, mitochondria and nucleus of the anoxic leaf cells became gradually disintegrated. Finally, under 72 h of submergence, the leaf cells became completely degraded with little condensed contents. The results indicated that the injury in membrane structure of various organelles, especially vacuole and chloroplast, was closely associated with the eventual demise of leaf cells of the submerged maize.

Cytochemical and ultrastructural studies indicated that compound spherical bodies observed near the sieve plate in the sieve tube members during the period of cambial dormancy in the shoots of Eucommia ulmoides Oliv. were polysaccharide bodies different from the polysaccharide grains in other parenchyma cells in shoots, and were similar to cell walls in their staining properties. The compound spherical bodies occurred in the sieve elements during the period of cambial rest and disappeared in the sieve elements during the period of cambial quiescence and activity.

A comparative study was carried out on the EM-cytochemical localization of calcium and Ca2+-ATPase activity in the suspension-cultured cells between the chilling-sensitive maize (Zea mays L. cv. Black Mexican Sweet) and chilling-insensitive Trititrigia (Triticum sect. Trititrigia mackey) at 4 ℃ chilling. When maize and Tyititrigia cells were cultured at 26 ℃, electron microscopic observations revealed that the electron-dense calcium antimonate deposits, an indication of the calcium localization, were localized mainly in the vacuoles, and few was found in the cytosol and nuclei. The electron-dense cerium phosphate deposits, an indication of Ca2+-ATPase activity, were abundantly distributed on the plasma membrane (PM). When the cells from both species were cultured at 4 ℃ for 1 and 3 h, an elevation of Ca2+ level in the cytosol and nuclei was observed, whereas the cerium phosphate deposits on the PM showed no quantitative difference from those of the 26 ℃-cultured cells, indicating that the enzymatic activities were not altered during these chilling periods. However, there was a distinct difference in the dynamics of the Ca2+ distribution and the PM Ca2+-ATPase activity between maize and Trititrigia when chilled at 4 ℃ for 12, 24 and 72 h. In maize cells, a large number of Ca2+ deposits still existed in the cytosol and nuclei, and the PM Ca2+-ATPase became less and less active, and even inactive at all. In Trititrigia cells, the increased cytosolic and nuclear Ca2+ ions decreased after 12 h chilling. By chilling up to 24 and 72 h, the intracellular Ca2+ concentration had been restored to a similar low level as those of the warm temperature-cultured cells, while the activity of the PM Ca2+-ATPase maintained high. The transient cytosolic and nuclear Ca2+ increase and the activities of PM Ca2+-ATPase during chilling are discussed in relation to plant cold hardiness.

杨树顶芽细胞内质网与其他膜系统的结构联系及其在休眠过程中的变化
简令成1* 李积宏1** 李本湘1*** 陈辉煌2

(1.Laboratory of Plant Hardiness,Department of Horticultyral Science, and Plant Biological Sciences Program, 2. Department of Horticulture, and Center for Gene Research and Biotechnology, Oregon State Unixersity,Corvallis,OR 97331, USA)

The Palaeovegetation Record of Monsoon Evolution in the Desert-loess Transition Zone for the Last 13 ka BPAuthor: LI Xiao-Qiang, ZHOU Wei-Jian, AN Zhi-Sheng, DONG Guang-Rong
Journal of Integrative Plant Biology 2000 42(8): 868-872

The study was to clarify the events of monsoon climate recorded by the palaeovegetation, using the results of pollen analysis, organic carbon δ13C, together with high-resolution 14C dating in the desert-loess transition zone for the last 13 ka BP. The palaeovegetation went though in the order of 9 periods viz.:desert-grassland,steppe,semi-desert,humid-grassland,desert,sparse-wood-grassland, desert-grassland, grassland, and desert grassland. The semi-desert, humid-grassland, and desert corresponded with the Younger Dryas events of cold-dry, cool-humid, and cold-dry climate after the end of the last glaciation. The optimum of the Holocene and other humid period between 4.5-3.5 ka BP were of high significance in research area.

Lectins and leghemoglobins in legumes play the important roles, respectively, in recognition of host plants to their own rhizobia, and lowering the oxygen partial pressure surround the bacteroids and protecting nitrogenase from oxygen in symbiotic nitrogen-fixing nodules.In order to investigate the non-leguminous recognition of rhizobial bacteria relating to nitrogen fixation, plant expression vectors containing pea lectin gene (pl) and Parasponia hemoglobin gene (phb) have been, respectively, constructed in a plasmid and the plasmid has been introduced into tobacco (Nicotiana tabacum L.) using Agrobacterium tumefaciens (Smith et Townsend) Conn as a vehicle for transformation. PCR and Southern blot demonstrated that the two genes were integrated into the genome of the tobacco plants. Histochemical staining for GUS activity, Western blotting,and in situ hybridization of pea lectin showed that they were expressed at translational level in the plants. These results may provide a clue for exploring whether Rhizobium leguminosarum bv. viciae could extend its host range and make the transgenic tobacco plants have the possibility of being symbiotic, or associative to nitrogen fixation.

The ultrastructure of the epidermis and flesh of apple (Malus domestica Borkh cv. Red Fuji) fruit was systematically observed during the fruit development via transmission electron microscopy. The results showed that, in spite of the ultrastructural changes in many aspects of the developing fruit epidermal cells, it remained almost unchanged throughout the whole developmental process that the cytoplasm was filled with numerous endoplasmic reticula (ER). Most of these endoplasmic reticula were tube-like and rough-ER with enlarged cisterna from which many vesicles were produced. Some of the vesicles were shown to merge into vacuole. Some dynamic Golgi bodies were also found. All the ultrastructural characteristics showed that the epidermal cells have the features of excretory cells. The ultrastructure of the fruit flesh cells at the young fruit stage were shown to be metabolically active, characterized by the presence of numerous clustered plasmodesmata, cisterna enlarged- and rough-ER filling the cytoplasm, plenty of vesicles and Golgi bodies, indicating their dynamic cellular transport function. Some giant-circular rough-ERs were found. All the ultrastructural features at this early developmental stage should be closely associated with the enlargement of the young fruit. At the rapid growing phase of the fruit the main changes were characterized by: the starch grain-filled amyloplasts, furcating of the single orifice of plasmodesmata, and the cytoplasm enrichment of both the Golgi body-formed vesicles and other vesicles. These features correspond well with those of a photoassimilate sink-cell. An ultrastructural degeneration phenomenon was observed at the fruit ripening stage, but the mitochondria and plasmalemma still remained intact, which might be related to the continuous development of fruit quality during the fruit ripening.

In order to efficiently introduce the genes of Aegilops triuncialisL. for resistance to powdery mildew into Triticum aestivum L., it is of importance to understand the genetic mechanism of their F 1 hybrid. It was shown that the bivalent frequency was higher than that of the theoretical value. It resulted from the combination of the wheat inhibitors of 5B Ph gene which located respectively on C and U genome of Aegilops triuncialis L. The results of chromosome in situ hybridization with the C genome-specific repetitive sequence, pAeca212, as the probe further indicated that some chromosomes of the C genome of Ae. caudata L. paired with the chromosomes of the other genomes.

The geographical distribution maps of the subgenus Pogonophace (Fabaceae: Astragalus) in China were designed and drawn using GIS cartographic technique. The species of the subgenus and county of China were treated as the basic composition units in the GIS cartographic technique. Most of the distribution maps were shown in spots. The distribution pattern of the subgenus illustrates that it is a peculiar group to adapt the cold alpine environment and distribute mainly in Hengduan Mountains and Himalayas. According to the geographical distribution maps and some statistic analyses, Hengduan Mountains region is suggested to be the distribution center, differentiation center and endemic center of the subgenus. Some vicariance traces at levels of the species or sections are very interesting among the distribution patterns of the subgenus and shown clearly in the maps.

The pollen grains in the atmosphere of Burdur have been studied for a two-year period (1996 through 1997) with a Durham sampler. A total of 11881 pollen grains belonging to 39 taxa have been identified and recorded with some unidentified ones. Of them, 5726 were identified in 1996 and 6155 in 1997. Of the total pollen grains, 76.51% were arboreal, 21.62% non-arboreal and 1.87% unidentified. The majority of the investigated pollen grains were from Pinus L., Cupressaceae, Gramineae, Quercus L., Platanus L., Chenopodiaceae/Amaranthaceae, Salix L., Cedrus L., Compositae, Juglans L. and Urticaceae respectively. The highest level of pollen concentration was in May.

The fossil specimens of Metasequoia Miki, aged in early Eocene was collected from Guchengzi and Jijuntun Formations of Fushun, Liaoning Province, Northeast China. Female and male cones and nutricious shoots, together with leafy epidermis and epidermis of staminal bract were investigated and here by described in details. The specimens is attributed to M. occidentalis after comparing them with M. glyptostroboides, M. milleri and M. occidentalis, considering the characteristics of leaves, female and male cones, epidermal cells and stomata. The average stomatal density of M. glyptostroboides in the stomatal distributional regions is measured to be 183.85/mm2, that of Fushun specimens 140.13/mm2; the average stomatal index of M. glyptostroboides in the stomatal distributional regions is 10.79, that of Fushun specimens is 9.48.

A Comparative Study on Photosynthesis and Water Use Efficiency Between Clonal and Non-clonal Plant Species Along the Northeast China Transect (NECT)Author: JIANG Gao-Ming, DONG Ming
Journal of Integrative Plant Biology 2000 42(8): 855-863

Net photosynthesis (P n), transpiration (E), stomatal conductance (g s) and water use efficiency (WUE) of more than 218 species belonging to two different reproductive functional types, i.e. clonal (115 species) and non-clonal species (103 species), along the 1 670 km Northeast China Transect (NECT) were analyzed. The results showed that P n and WUE appeared to be lower in the east and west ends of NECT, with peaks in the middle. Transpiration was found to be higher in the west end, where most temperate desert species were distributed. On the same site, most clonal species showed higher P n and related physiological variables than non-clonal species. For different growth forms over NECT, e.g. forest trees, shrubs and grasses, meadow steppe shrubs and grasses, typical steppe shrubs and grasses, the meadow steppe and typical steppe grasses, showed higher values of physiological variables than the forest or the desert species. But for the two reproductive plant functional types (PFTs), clonal species had higher physiological variables, with averages of 22%, 15%, 23% and 14% higher than the non-clonal ones for P n, E, gs, and WUE, respectively. Such differences indicated that clonal species might have advantages over non-clonal species in utilizing environmental resources such as light, CO2, and especially water.

Six species of marine microalgae, viz., Nitzschia closterium Ehr.,Chaetoceros muelleri Lemm., Phaeodactylum tricornutum Bohl., Isochrysis galbana Parke 8701, Platymonas subcordiformis (Wille) Hazen and Chlorella vulgaris Beij. exhibited different sensitivities to 5 kinds of antibiotics. Among the 5 kinds of antibiotics, chloromycetin was the common sensitive antibiotic for the 6 species of marine microalgae. Its 72 h EC 50 (50% effective concentration) was from 56-289 mg/L, which made chloromycetin the reasonable selective marker for the 6 species of marine microalgae．Thus, CAT （chloramphenicol acetyltransferase） gene could be widely used as selective marker in the study of marine microalgal genetic engineering． Moreover, Chaetoceros muelleri was sensitive to kanamycin and ampicillin, and Phaeodactylum tricornutum was sensitive to ampicillin, therefore, NTPⅡ (neomycin phosphotransferaseⅡ) gene and Ampr (Ampicillin resistant) gene could be used as selective marker for Chaetoceros muelleri, and Ampr gene for Phaeodactylum tricornutum.

State Key Basic Research and Development Plan of China: Dynamics and Sustainable Use of Biodiversity and Regional Ecological Security in the Yangtze ValleyAuthor: ZHAO Li-Hui
Journal of Integrative Plant Biology 2000 42(8): 879-880